The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.
Gas scrubbing is one method of reducing industrially produced carbon dioxide. The most widely used gas scrubbing process involves scrubbing of a gas using an absorption medium, typically an aqueous alkaline solvent solution. The process is regenerative through the continuous recirculation of the absorption medium between an absorption stage where carbon dioxide is absorbed into the absorption medium and a regeneration stage in which carbon dioxide is desorbed from the absorption medium.
The combustion gas produced from bulk combustion processes such as coal or gas-fired power stations require large scale gas scrubbing plants to process the emissions. The overall size that traditional welded metal framework process vessels can be constructed for this purpose is limited by transport and structural strength considerations. In this respect, road transport regulations in many countries place a limit on the size (height and width) of loads which can be transported. In addition, most vessels of this type are transported on their sides due to height restrictions of overhead structures (bridges, powerlines etc.) Wall strength considerations therefore limit the size of a vessel that can be transported in this manner. Such process vessel size restrictions limit the economic viability of constructing large scale plants that include large scale process vessels.
U.S. Pat. No. 5,221,304 discloses a pressure swing adsorption vessel containing a bed of absorbent configured to address some of the above size restriction issues. The vessel is constructed with a top and base having gas distribution ports formed therein and having sidewalls of concrete which are lined with a gas and moisture-impermeable material. The vessel is designed to be constructed and located underground. However, the construction and configuration of this vessel is not ideally suited to combustion gas scrubbing applications.
It is therefore desirable to provide alternative process vessels and a process plant using these vessels for gas scrubbing of post combustion gas streams.